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Azobenzene

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https://www.readbyqxmd.com/read/28350435/insight-into-a-fast-photo-tuning-azobenzene-switch-for-sustainably-tailoring-foam-stability
#1
Shaoyu Chen, Yanyan Zhang, Kunlin Chen, Yunjie Yin, Chaoxia Wang
A photo-responsive surfactant of 4-octoxy-4'-(trimethylaminoethoxy) azobenzene (OTAEAzo) has been synthesized for developing a fast photo-tuning foam switch based on its high sensitivity, reversibility and fatigue resistance of photo-isomerization capability. Ultraviolet (UV) light irradiation for 1 s enabled the conversion from trans isomer to cis configuration, while exposing to visible (Vis) light for 3 min induced cis-to-trans transformation, which maintains an excellent cycling stability for 20 cycles of photo-isomerization...
March 28, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28346548/kinetics-of-light-induced-ordering-and-deformation-in-lc-azobenzene-containing-materials
#2
Vladimir Toshchevikov, Tatiana Petrova, Marina Saphiannikova
Azobenzene-containing smart materials are able to transform the energy of light into directional mechanical stress. We develop a theory of time-dependent light-induced ordering and deformation in azobenzene materials starting from the kinetic equations of photoisomerization. The liquid crystalline (LC) interactions between rod-like trans-isomers are taken into account. Angular selectivity of the photoisomerization known as an "angular hole burning" or the Weigert effect leads to the light-induced ordering and deformation of the azobenzene materials...
March 27, 2017: Soft Matter
https://www.readbyqxmd.com/read/28338244/photoalignment-of-vertically-oriented-microphase-separated-lamellae-in-lc-lc-diblock-copolymer-thin-film
#3
Koichiro Beppu, Yuki Nagashima, Mituo Hara, Shusaku Nagano, Takahiro Seki
The microphase separation and photoalignment behavior of a diblock copolymer consisting of two kinds of side chain liquid crystalline (LC) polymers are investigated. Here, the mesogens of photoresponsive azobenzene and non-photoresponsive cyanobiphenyl are introduced in the side chains. The azobenzene and cyanobiphenyl mesogens orient homeotropically and planarly, respectively, in a thin film state. The combination of these contrasting orienting properties leads to a formation of vertically oriented lamella in the microphase separation structure...
March 24, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28328218/functionalized-lanthanide-iii-complexes-constructed-from-azobenzene-derivative-and-%C3%AE-diketone-ligands-luminescent-magnetic-and-reversible-trans-to-cis-photoisomerization-properties
#4
Li-Rong Lin, Hui-Hui Tang, Yun-Guang Wang, Xuan Wang, Xue-Ming Fang, Li-Hua Ma
The coordination ability of ligands functionalized by azobenzene was manipulated, and two novel chelating ligands, (E)-4-(phenyldiazenyl)-N,N-bis(pyridin-2-ylmethyl) benzohydrazide (C25H22N6O, PBPM) and (E)-4-((4-(dimethylamino)phenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl) benzohydrazide (C27H27N7O, dmPBPM), were synthesized. The ligands can offer four coordinating atoms (one oxygen and three nitrogens) to act as tetradendate ligands, together with the two β-diketonates (4,4,4-trifluoro-1-phenylbutane-1,3-dionate, tfd), and the trifluoroacetate anion presented as a ligand and a counterion to form the quaternary units with lanthanide(III) ions (La, Eu, and Gd), [Ln(tfd)2(PBPM)(CF3CO2)] (LnC47H34F9N6O7) and [Ln(tfd)2(dmPBPM)(CF3CO2)] (LnC49H39F9N7O7), where the lanthanide(III) ions are nine coordinated with N3O6 donor sets...
March 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28298105/photoswitching-of-azobenzene-containing-self-assembled-monolayers-as-a-tool-for-control-over-silicon-surface-electronic-properties
#5
Ivan V Malyar, Evgenii Titov, Nino Lomadze, Peter Saalfrank, Svetlana Santer
We report on photoinduced remote control of work function and surface potential of a silicon surface modified with a photosensitive self-assembled monolayer consisting of chemisorbed azobenzene molecules (4-nitroazobenzene). It was found that the attachment of the organic monolayer increases the work function by hundreds of meV due to the increase in the electron affinity of silicon substrates. The change in the work function on UV light illumination is more pronounced for the azobenzene jacketed silicon substrate (ca...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28296419/selective-lithiation-magnesiation-and-zincation-of-unsymmetrical-azobenzenes-using-continuous-flow
#6
Marthe Ketels, David B Konrad, Konstantin Karaghiosoff, Dirk Trauner, Paul Knochel
A mild and general set of metalation procedures for the functionalization of unsymmetrical azobenzenes using a commercially available continuous-flow setup is reported. The metalations proceed with TMPLi under convenient conditions (0 °C, 20 s), and various classes of electrophiles can be used. With sensitive substrates, an in situ trapping metalation in which TMPLi is added to a mixture of the azobenzene and ZnCl2 or MgCl2·LiCl was very effective for achieving high yields.
March 15, 2017: Organic Letters
https://www.readbyqxmd.com/read/28282043/photoswitching-of-glass-transition-temperatures-of-azobenzene-containing-polymers-induces-reversible-solid-to-liquid-transitions
#7
Hongwei Zhou, Changguo Xue, Philipp Weis, Yasuhito Suzuki, Shilin Huang, Kaloian Koynov, Günter K Auernhammer, Rüdiger Berger, Hans-Jürgen Butt, Si Wu
The development of polymers with switchable glass transition temperatures (Tg) can address scientific challenges such as the healing of cracks in high-Tg polymers and the processing of hard polymers at room temperature without using plasticizing solvents. Here, we demonstrate that light can switch the Tg of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers. The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization abilities...
February 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28272864/body-temperature-controlled-optical-and-thermal-information-storage-light-scattering-display-with-fluorescence-effect-and-high-mechanical-strength
#8
Si Chen, Xiaoqian Tong, Huiwen He, Meng Ma, Yanqin Shi, Xu Wang
A kind of body temperature controlled optical and thermal information storage light scattering display based on super strong liquid crystalline physical gel with special "loofah-like gel network" was successfully prepared. Such liquid crystal (LC) gel was obtained by mixing a dendritic gelator (POSS-G1-BOC), an azobenzene compound (2Azo2), and a phosphor tethered liquid crystalline host (5CB), which could show its best contrast ratio at around human body temperature under UV light because of the phosphor's fluorescence effect...
March 27, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28263056/gold-superparticles-functionalized-with-azobenzene-derivatives-sers-nanotags-with-strong-signals
#9
Ying Ma, Kittithat Promthaveepong, Nan Li
The surface-enhanced Raman spectroscopy (SERS) nanotag was proposed as a substitute for fluorescent dye for imaging and biosensors several decades ago. However, its weak signal and poor reproducibility has hindered its application. Here, we report a new strategy to form Au superparticles (AuSPs) with high SERS enhancement via one-pot formation and self-assembly of Au nanoparticles (NPs). An azobenzene-carrying Raman reporter was synthesized to exhibit a large Raman cross-section and multiple bands. The self-assembly of the Raman reporter on AuSPs generated SERS nanotags with intense signals...
March 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28256662/humidity-induced-formation-of-water-channels-in-supramolecular-assemblies-of-wedge-shaped-amphiphiles-the-effect-of-the-molecular-architecture-on-the-channel-topology
#10
A Dolgopolov, K N Grafskaia, D V Anokhin, D E Demco, X Zhu, D A Ivanov, M Möller
In supramolecular assemblies, absorption of water can assist the channel formation, similarly to biological systems and Nafion-like commercial ion-selective membranes. In this work, we investigate humidity-induced formation of water channels in wedge-shaped amphiphilic molecules, namely sodium 4'-[3'',4'',5''-tris(alkyloxy)benzoyloxy]azobenzene-4-sulfonates. The studied molecules contain a polar sulfonate group at the tip and a hydrophobic periphery composed of alkyl chains of two different lengths. Upon increasing the relative humidity (RH) the amount of absorbed water significantly increases for the mesogen with dodecyl chains as compared to the one with octyl groups...
March 3, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28254338/controlled-co-release-of-doxorubicin-and-reactive-oxygen-species-for-synergistic-therapy-by-nir-remote-triggered-nanoimpellers
#11
Beibei Hou, Weitao Yang, Chunhong Dong, Bin Zheng, Ying Zhang, Jing Wu, Hanjie Wang, Jin Chang
How to encapsulate and transport the payload of multiple therapeutic compounds avoiding premature leakage, and simultaneously co-release them rapidly at specific lesions still remains the major concern in clinic. Herein, we designed the UCN@mSiO2-(Azo+RB) (azobenzene groups and Rose Bengal) nanoimpellers, which used the multicolor-emission capability of the core-shell upconverting nanoparticles (UCNs) at a single excitation wavelength to co-release anticarcinogen doxorubicin (Dox) and reactive oxygen species (ROS) for combined chemotherapy and photodynamic therapy (PDT)...
May 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28252300/triggering-on-off-states-of-photoswitchable-probes-in-biological-environments
#12
Silvio Osella, Stefan Knippenberg
The use of hybrid systems for which the change in properties of one component triggers the change in properties of the other is of outmost importance when "on/off" states are needed. For such a reason, azobenzene compounds are one of the most used probes due to their high photoswitching efficiency. In this study, we consider a new derivative of azobenzene interacting with different lipid membrane phases as a versatile fluorescent probe for phase recognition. By means of a multiscale approach, we found that the cis and trans conformers have different positions and orientations in the different lipid membranes (DOPC for the liquid disordered phase and DPPC for the gel phase), and these have a profound effect on the optical properties of the system, for both one and two photon absorption...
March 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28240890/tetra-meta-butylcarbamoyl-azobenzene-a-rationally-designed-photoswitch-with-binding-affinity-for-oxoanions-in-a-long-lived-z-state
#13
Kajetan Dąbrowa, Janusz Jurczak
A new photoswitchable anion receptor 1 based on a tetra-meta-substituted azobenzene skeleton has been readily synthesized in two steps. Titration studies ((1)H NMR) and theoretical predictions (DFT/M06-2X/6-31G(d)/DMSO-SM8) revealed that nonplanar Z-1 is a better host for anions than E-1, which results from the greater ability of four amide NH protons in the Z-state to cooperatively bind oxoanions, in particular tetrahedral H2PO4(-) and H2AsO4(-). Furthermore, the thermal decay of Z-1 (τ1/2 = 11 days) is not accelerated by anion binding...
February 27, 2017: Organic Letters
https://www.readbyqxmd.com/read/28240752/azobenzene-based-ruthenium-ii-catalysts-for-light-controlled-hydrogen-generation
#14
A Telleria, P W N M van Leeuwen, Z Freixa
Eight new ruthenium(ii) half-sandwich complexes containing azobenzene-appended pyridine (1), bipyridine (2-5) and phosphine (6 and 7) ligands have been synthesized and fully characterized. UV-vis spectroscopic studies showed that the trans-to-cis photoisomerization was strongly inhibited upon coordination to the metal centre in azopyridine-derived ligands 1 and 2, but it remained efficient in azobenzene-appended bipyridine (3-5) and phosphine (6 and 7) ligands. The complexes were tested as precatalysts for photo-controlled hydrogen generation by hydrolytic decomposition of ammonia-borane (AB)...
March 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28230888/pd-cu-cooperative-catalysis-an-efficient-synthesis-of-3-isoindazolyl-allenes-via-cross-coupling-of-2-alkynyl-azobenzenes-and-terminal-alkynes
#15
Chuan Zhu, Chao Feng, Motoki Yamane
An efficient synthesis of (3-isoindazolyl)allenes from 2-alkynyl azobenzenes and terminal alkynes via cooperative Pd(PPh3)2Cl2/CuI-catalyzed cross-coupling has been developed. By making use of this approach, (3-isoindazolyl)allenes with various substituents can be synthesized in good to excellent yields. A rapid synthesis of biologically active indazolo[2,3-a]quinoline was also achieved using this method as the key step.
February 23, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28230805/preparation-of-photoirradiation-molecular-imprinting-polymer-for-selective-separation-of-branched-cyclodextrins
#16
Haoran Fan, Jinpeng Wang, Qingran Meng, Xueming Xu, Tianming Fan, Zhengyu Jin
In the present study, photoirradiation molecularly imprinted polymer (MIP) with azobenzene was used as a functional monomer for the selective separation of the branched cyclodextrins. The functional monomer 4-methacryloyloxy azobenzene (MAA) and the molecular template 6-O-α-d-maltosyl-β-cyclodextrin (G2-β-CD) were implemented for the molecular imprinting. The core-shell structure of photoirradiation MIP was visualized by the transmission electron microscopy (TEM). With Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), we identified that G2-β-CD was imprinted into the polymer and removed from the MIP...
February 21, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28230215/graphene-modulated-photo-absorption-in-adsorbed-azobenzene-monolayers
#17
Qiang Fu, Caterina Cocchi, Dmitrii Nabok, Andris Gulans, Claudia Draxl
The impact of graphene on the photo-absorption properties of trans- and cis-azobenzene monolayers is studied in the framework of density-functional theory and many-body perturbation theory. We find that, despite the weak hybridization between the electronic bands of graphene and those of the azobenzene monolayers, graphene remarkably modulates the absorption spectra of the adsorbates. The excitation energies are affected via two counteracting mechanisms: substrate polarization reduces the band-gap of azobenzene, and enhanced dielectric screening weakens the attractive interaction between electrons and holes...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28224157/smart-worm-like-micelles-responsive-to-co2-n2-and-light-dual-stimuli
#18
Jianzhong Jiang, Guozheng Wang, Yuxuan Ma, Zhenggang Cui, Bernard P Binks
CO2/N2 and light dual stimuli-responsive worm-like micelles (WLMs) were obtained by addition of a relatively small amount of a switchable surfactant, 4-butyl-4'-(4-N,N-dimethylhexyloxy-amine) azobenzene bicarbonate (AZO-B6-CO2), sensitive to the same triggers to a binary aqueous solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal).
February 22, 2017: Soft Matter
https://www.readbyqxmd.com/read/28222261/enhanced-release-of-molecules-upon-uv-light-irradiation-from-photoresponsive-hydrogels-prepared-from-bifunctional-azobenzene-and-four-arm-poly-ethylene-glycol
#19
Shiva Kumar Rastogi, Hailee E Anderson, Joseph Lamas, Scott L Barrett, Travis Cantu, Stefan Zauscher, William J Brittain, Tania Betancourt
Advances in biosensors and drug delivery depend on hydrogels that respond to external stimuli. In this work we de-scribe the preparation and characterization of photoresponsive hydrogels prepared by crosslinking of di-NHS ester of azobenzoic acid and four-armed, amine-terminated poly(ethylene glycol). The porous structure and composition of the hydrogels were confirmed by scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The reversible photoisomerization of the azobenzene-containing hydrogel crosslinkers in the gels was confirmed by ab-sorption spectroscopy...
February 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28221015/taking-orders-from-light-photo-switchable-working-inactive-smart-surfaces-for-protein-and-cell-adhesion
#20
Junji Zhang, Wenjing Ma, Xiao-Peng He, He Tian
Photoresponsive smart surfaces are promising candidates for a variety of applications in optoelectronics and sensing devices. The use of light as an order signal provides advantages of remote and noninvasive control with high temporal and spatial resolutions. Modification of the photoswitches with target biomacromolecules, such as peptides, DNA, and small molecules including folic acid derivatives and sugars, has recently become a popular strategy to empower the smart surfaces with an improved detection efficiency and specificity...
March 2, 2017: ACS Applied Materials & Interfaces
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